Molecular tools for selection and characterisation of lactic acid bacteria associated to Patagonian red wines

Abstract

The selection of lactic acid bacteria (LAB) from a wine-producing area is necessary to the formulation of native malolactic starter cultures, well adapted to local winemaking practices, and able of enhancing the regional wine typicality. In this sense, molecular biology techniques are fundamental tools to the study of the native microbiome involved in the alcoholic (AF) and malolactic fermentations (MLF), as well as to selection of yeasts and bacteria and its technological and oenological characterization. In our laboratory, the analysis of native LAB community, present in spontaneous MLF stage of Patagonian Pinot noir and Merlot wines, by culture-independent methods (PCR-rpoB/DGGE, and PCR-16S rRNA-V3/DGGE), allowed identifying several LAB species, being Oenococcus oeni and Lactobacillus plantarum the prevalent ones. Different isolates of these two species were also largely recovered by culture and then analyzed by RAPD PCR with Coc primer, revealing a high intra-species genetic heterogeneity. On the other hand, the use of PCR allowed us the study of oenological properties such as the absence of biogenic amines synthesis, and the presence of genes related to wine aroma compounds. Based on these approaches, several strains of O. oeni and Lb. plantarum were selected to evaluate them at technological level, analyzing their malolactic performance and implantation capacity in vinification assays, at laboratory scale. The performance of a psychrotolerant strain of O. oeni was also studied. In this context, we have established a working platform to carry out studies of microbial communities of oenological interest, selection of strains of potential interest as malolactic cultures and evaluation of its impact on the quality and flavouring properties of regional wines.